This invention relates to antennas used on portable devices. More specifically, the invention involves the design of an antenna for a portable transceiver device to reduce the exposure of its user and bystanders to electromagnetic transmissions emitted from the device.
Technological progress in the field of electronics has broadened the availability of affordable yet sophisticated portable communication devices. For example, consider the cell or wireless phone. Such transceiver devices provide users with the convenient ability to talk with associates, family and friends even while on the move. More recently, these devices have offered users the ability to send and receive digital information including electronic mail and even surf the Internet from almost any location. Thus, it is no surprise that the devices are widely used. Moreover, while the number of present users of such devices is staggering, with new advancements and improvements, the numbers will only continue to grow.
However, increased convenience should not come at the cost of personal safety. In recent years, the proliferation of such devices has generated some cause for concern. Since each transceiver device requires the ability to transmit information to some external location without the use of a physical channel or wire, each device must be equipped with a radio-frequency (RF) transmitter. Typically, these RF transmitters generate Ultra High Frequency (UHF) electromagnetic carrier waves in the region of 300 to 3000 MHz. Since these waves emanate from these devices in close proximity to their users and bystanders, the potential negative health effects of UHF radiation exposure has entered the public arena. For example, the effect of UHF radiation as a cause of cancer is addressed in JE Moulder et al: Cell Phones and Cancer: What Is the Evidence for a Connection? Radiation Research 151(5):513-531, May 1999; see also KR Foster and JE Moulder: Are mobile phones safe? IEEE Spectrum, August 2000, p. 23-28.
At least one prior art antenna has attempted to minimize the risks of cancer due to the exposure to RF radiation transmitted from a hand-held communications device. In the patent to Chang, U.S. Pat. No. 6,097,340, an antenna with a semi-cylindrical shield is used to limit the direction of radiating RF waves of a cell phone. The shield is intended to cover the side of the core of the antenna that faces the cell phone user. However, the antenna has an important shortfall. The antenna provides only limited protection. As designed, the antenna provides no shielding for non-users of the phone who are still in close proximity to the RF radiation from the side of the core opposite the shield.
An objective of the present invention is to provide an antenna for a portable communications device that reduces the user""s exposure to RF radiation emitted from the device.
A further objective of the present invention is to provide an antenna for a portable communications device that reduces bystanders"" exposure to RF radiation emitted from the device.
A still further objective of the present invention is to provide such an antenna while maintaining the antenna""s effectiveness.
An additional objective is to provide an antenna with improved signal transmission capabilities.
Additional objectives will be apparent from the description of the invention as contained herein.
In its broadest aspects, the present invention involves an antenna for hand-held communications devices such as a cell phone, beeper, portable computer/organizer with RF transmission capabilities, portable Internet access device or other transmitter emitting RF radiation. In its preferred embodiment, the antenna utilizes a unique directing shield with a design intended to minimize RF radiation exposure by users and bystanders in close proximity to the device while simultaneously maximizing directional transmission toward the intended receiver of the signal. In general, the directing shield combines a concave shield wall with one or more semi-conic buds. The shield wall and semi-conic buds are treated with or molded from a transmission blocking/reflecting material. The directing shield is positioned over a linear cylindrical rod or conducting member of the antenna. The combined directing shield and conducting member are encased by a resin or plastic shell. The conducting member extends from the encasing for connection to RF transmission circuitry of a communications device.
In one embodiment of the invention, the antenna is configured with a bend angle to maximize transmission in the desired direction and away from its user and bystanders. while the portable device is in use. In another embodiment, the antenna has a collapsible/extendible portion to allow the antenna to be raised and lowered. In a further embodiment, the antenna can swivel at its base so that the directional alignment of the bud or buds may be adjusted when the portable device is used in alternative positions.